Many types of fire extinguishers are known for protecting buildings or accommodation areas in general. Some of these are connected to the water mains or to a voluminous water storage tank and extinguish a fire by means of water. This manner of extinguishing a fire is unsuitable in spaces in which is located equipment which can be damaged by water. When electrical components are for instance located in the space, the water can cause short-circuiting. Even if the water is able to extinguish the fire, the components will in many cases have become useless due to the water. The known extinguishers moreover have quite a large size, which makes them unsuitable for use in protecting relatively small objects.
For the protection of inner spaces of smaller objects such as machines or hardware against fire, fire extinguishers are further known in which a pressure cylinder, which is provided with an extinguishing agent (gas, liquid or solid) is stored under overpressure. In the case of fire the pressure cylinder is opened and the extinguishing agent is guided outward as a result of the overpressure. A drawback of the known fire extinguishers is that the extinguishing agent present therein often has an adverse effect on the inner space in question. The known extinguishing agents are moreover harmful in greater or lesser degree to the environment and to humans. Finally, the known fire extinguishers are unsuitable for placing inside objects.
In addition, aerosol-forming fire extinguishers are known in which, after activation of the fire extinguisher, the extinguishing agent is converted into an aerosol which is carried into the inner space. An example of such an aerosol-forming fire extinguisher is the fire extinguisher known under the brand name “FirePro®”. After thermal (including electrical) activation, the extinguishing agent stored in a container in the fire extinguisher is converted into an aerosol which does not combat fire so much by making use of conventional methods based only on smothering or based only on cooling, but by ending the combustion reaction on a molecular basis. The free radicals present in the fire are herein bonded by the generated aerosol without affecting the local oxygen content. These extinguishing elements have the advantage that a fire is extinguished quickly and efficiently without this resulting in appreciable damage to the environment, people or to the object itself. After the cause of the fire has been removed and the aerosol optionally blown out of the closed space, the object can in many cases be used again immediately without delay, even if sensitive equipment such as electronic components is placed in the inner space. The inner space in general and the electronic components in particular in any case remain unaffected by the aerosol.
The known aerosol-forming fire extinguishers are activated when the temperature of the extinguishing material in the container reaches a determined minimum value. When a fire therefore breaks out, the temperature of the extinguishing material will increase due to heat penetrating into the container. When said minimum temperature is reached, the extinguisher is activated by transformation of the extinguishing material into expanding extinguishing aerosol. A drawback of the known aerosol-forming fire extinguisher is that the activating temperature is quite high (typically in the order of magnitude of +/−330 °C.) so that the fire extinguisher is switched on relatively late and the damage resulting from the fire can thereby be considerable. The activating temperature for a specific fire extinguisher furthermore has a fixed value.
In order to obviate this drawback it is known to provide the aerosol-forming fire extinguisher with a thermally conductive cord which extends partly outside and partly inside the container of the fire extinguisher. The thermo-cord is placed in the vicinity of possible sources of fire. As soon as there is fire, and therefore generation of heat, heat is conducted via the cord into the container of the fire extinguisher. This means in practice that the fire extinguisher can already be activated at lower ambient temperatures (such as at about 172° C.). The activating temperature however remains determined mainly by the composition of the extinguishing material, and therefore has a (practically) fixed value for a specific fire extinguisher. However, since the fire extinguisher must already be switched on in the one object at an earlier stage, for instance at a lower temperature, than in another object, the known fire extinguisher is less suitable for universal application.
From the American document WO 03/024534 A1 a system is known for suppressing fire in the freight compartment of a passenger aircraft. Outside the compartment for protecting there are placed a number of housings provided with aerosol fire-extinguishing units. The extinguishing elements can blow the aerosol into the compartment via openings in the ceiling of the compartment. A number of separate smoke detectors are also arranged in the ceiling. The extinguishing units and smoke detectors are connected to a data network and a central control unit (cargo fire detection control unit). The activation of the extinguishing elements is therefore effected centrally by means of an external control unit. The known system is thereby complicated and costly, and moreover sizeable, so that it is less suitable for arranging in the small inner space of an object such as a switch cabinet, a computer or the like. The known system is also unsuitable for arranging in the inner space of the object for protecting against fire because the control unit and the wire network are arranged outside the housing and are thereby sensitive to fire.